High-frequency oscillator



Feb. 25, 1947.- w. HoTlNE 2,416,319

HIGH FREQUENCY OSCILLATOR Filed oct.- 8, 1942 2 sheets-sheet i Feb. 25, 1947. w. HoTlNE .HIGH FREQUENCY oscILLAToR Filed oct. 8, 1942 sheets-sheet 2 J'NVENToR. WML/4M Hor/NE Patented Feb. 25, 1947 UNITEDl STATES Parleur-v OFFICE HiiGH-FREQUENCY OSCILLATOR l. corporation of Delaware Application October 8, 1942, SerialA No. 461,305

rIhis invention relates to improvements in high frequency oscillators, and more particularly to such oscillators of the type wherein a vacuum tube forms a mechanical unit with the oscillator tank circuit.

An object of this invention is to obtain higher oscillator frequencies than heretofore possible with vacuum tube oscillators using standard types of vacuum tube. i

Another object of this invention is to provide a novel high frequency vacuum tube tank oscillator in which the plate-to-ground capacitance is lower than in comparable arrangements now known tothe art.

Still another object of this invention is to provide a novel and improved high frequency oscillating circuit for a vacuum tube having eX- ternally shield electrodes.

Other objects and advantages of the present invention will appear from the vfollowing description of a preferred physical embodiment of the invention as well as from the described circuit connections therefor, all illustrated in the accompanying drawings, wherein:

Fig. l is a longitudinal cross-sectional view of an improved tank oscillator formed in accordance with the present invention, and also diagrammatically illustrates the circuit connections therefor;

Fig. 2 is a transverse cross-sectional View of the oscillator illustrated in Fig. l, taken along the line 2 2; n

Fig. 3 is a circuit diagram illustrating the relationship between the electrodes and the ex-i ternal leads of the vacuum tube shown in Fig. 1;

Fig. 4 is a complete circuit diagram ofthe tank oscillator illustrated in Fig. l;

Fig. 5 is a diagrammatic representation of the relationship between the 'electrodes of the vacuum tube shown in Fig. l, together with a circuit diagram of the externai oscillating circuit connections; and

Fig, 6 is a circuit diagram illustrating the basic high frequency oscillating circuit of the oscillator illustrated in Fig. l.

A preferred physical embodiment of my irnproved tank oscillator is shown Figs. l and 2, and is drawn to enlarged scale for. the sake ci clarity. In these figures the oscillatorv as a whole is designated by the reference numeral and consists essentially of two coaxial lines i2 and ifi in the iorin of resonant cavities. The coaxial line i2 may consist of concentric metal cylinders iii and 2d having a metal rngli slid.- able therebetween, lthe outer cylinder I8 being 12v claims. (ci. 25o- 36) `able ring 2l 4movable between them.

preferably common Vto both coaxial lines l2 and Hi, and, as more clearlydescribed hereinafter, the inner cylinder 2o forming a reactive anode conductor for. the oscillator. The coaxial line Id is formed by the outer metal cylinder I8, the inner concentric metal cylinder 22 and the slid- Between the resonant lines I2 and I4 and intermediate the ends of the common outer cylinder i8, is positioned a metal disk 24 whose outer periphery isin electrical contact with the inner surface of the cylinder. The disk 24 is open at its center and rigidly supports the outer metallic ring 2S of a vacuum tube socket 23 extending through the opening in the disk 24 and supported coaxially relatively vto the cylinder I8. The socket 2S is adapted to receive a vacuum tube of a type well kno-wn in the art. lThis tube is provided with a metallic strengthening shield 32 surrounding the electrode elements therein, the glass bulb serving merely forsealing and gripping purposes, and with a metal plug 34 which is locked in the socket 28 and which is electrically connected with the shield 32. The tube which has been illustrated, by way of eX- arnple, may be of the type known as the Sylvania 1201 tube, although it is to be distinctly understood that the invention is not to be limited to use in co-nnection with this or any other specie vacuum tube. v

The disk 2d, in addition'to supporting the vacuum tube socket 2B, also preferably supports and forms part of aI condenser 35 which consists of a thin metal sheet 38 ,separated from the disk 24 by a thin sheet of insulating material lill. It wil1 be clear to those skilled in this artl that the plates of the condenser 36 are, in this case,

formedv by the metal sheet 38, on the one hand, Y

and the disk itself on the other hand. A resistor l2 is preferably connected across the condenser 36. i

Mounted within the. reactive anode conductor 2i) of the coaxial line l2 is an `anode supply lead in theV form of a rod M, one'end of which isA pro-vided with an enlarged head having a conical surface 46 spaced from a corresponding inner conical surface 48 formed on the inner` endofv supply,'I prefer to connect another condenser 54 between the outer end of the rod 45 and the cuter end of the reactive anode conductor 2(l.` vThis condenser may be mounted in the space be- Ir tween the rod 44 and the reactive anode conductor 2B.

The innercylinder 22 of the. coaxial Vline I 4v will engage the metal shield 32 of the inserted vacuum tube 3U, and forms a reactive cathode conductor, as will be explained in more detail hereinafter. Y

The manner in which the electrodes of'the vac-l uum tubes are interconnected with the afore` described constructional elements of the oscillator will now be describedand in this connectionv reference is made to Fig. 2 as well as to'Fig. 1. The socket 28 mounted within the disk 2:1 is of the usual type being provided with spaced elec` ner that, for example, connectorsES and Se will"Y lead to` the anode P, the Yconnectors r@tand tft` A2,416,319 y i g i 5 to the cathode K, the connectors 62 and 'loto the gridG and the. connectors 38 and 'l2 to the heater F. `This arrangement of diametrically op- Y posed anode andrgrid connectors is particularly adaptable for the type of oscillator contemplated since it permits theuse of extremely short leads,

important in ultrahigh frequency circuits. The type of socket V28 commonly usedin the art is also providedY with spacedv spring contacts 14,16, and 18 which are adapted to engage and holdrthe` metal plug 34 which, asprevious'ly described, isY

also electricallyfconnected tothe external shieldv 432 Ysurrounding the vacuum tube electrodes. Applcantalso takes advantage ofV this constructional arrangement to providevshort leads for the high frequency oscillator circuit. o; Aswill be seen kfrom a study of Figs. 1 and 2 the anode connectors 58 and will be attached by shortpleads 8E! and 82,respectively to the rod 44 leading, on theV one'hand, to the reactive an-` ode conductor 20 through the'condenser 52 and,V onthe Yotherhand, to a suitable high ,potential i v.source B+. fThe grid connectors Q2 and l0 will be attached to the metal sheet 38 forming one Y plate of theY condenser 36 by the shortleads 84 and 86. The cathode connections 160 andY 64 may berdirectly attached, as by soldering to the spring member 14 sothat, in this case, the cathode iseiectvely directly connected to theY shield 32.Y One of Y, the heater connectors 121s likewise directly soldered to a spring member 18 which, as previously described, is also electrically interconnected with the shield 32. ,The other heater-connector Bis attached throughV a lead 8B tov a low potential source A+. In order to bring the lead 88 out'of Vthe oscillator for con` nection to the low potential source A+, I prefer'- ably providea small opening Si) through one portion `of the condenser'SB and extend the lead At8 through this opening in the form of a line, $2 runningY parallelY to the cathode line 22 of the coaxialV line YI4. The line92 will then pass through another opening 84 in the'cylinder ,22 and then outwardly through the open end of the oscillator. A condenser SSmay be connected at any suitable point between lthey line 92y and the cylinder 22 and `this,infconne`ction with a Vhigh vfrequency Y anode P, on the other hand,is connected to ground 4 choke '98,' will prevent the flow of high frequency currents to the direct current circuit. Similarly,

in the connection Vto ther high potential source B+, a suitable high frequency choke may be inserted.

Keeping in mindV that at the frequencies contemplated, the internal capacities cf the tube and the capacities betweenV the various electrodes and Vthe surrounding metallic shield 32 actually form part of the oscillator circuit, reference is next made to Fig. 4 which illustrates the complete ciry cuit diagram of the oscillator whose constructional features have just been described. In Fig. 4 the metallic shield 32 has been indicated as a box about the electrodes'of the tube 3c. Considering, first ofall, the inter-electrode capacities, it will be clear that there exists a capacitance Cpg between the anode P and the grid'G, a capacitance Cpk between the grid G and the cathode K. The capacitance between the anode and the shield 32 is indicated at 'Cpe while the capacitance be-l. tween the grid G and the shield 32 is represented by Cgs. As the cathode is directly connected to the shield 32 in the mannerdescribed above, there a a Y will be no capacitance between these parts.

A study of the circuit shown in Fig. 4 will reveal the novel feature of the present yinvention whereby the grid is grounded for high frequency currents and the shield 32 is connected to the cathode K which, in this case, is a swinging electrode, being isolated from ground at the frequencies contemplated by the cathode conductor 22. The grid G is connected to the outer cylindrical member` I8 of the oscillator through condenser 36 and shunt resistor i2 and, as shown in Fig. l, the outer cylinder ii''isgrounded.` The only through condenser 52 and reactive anode conductor 2B and the cathode with the 'shield 32 are only connected to ground through the reactive cathode conductor 22.

The advantages of this circuit which permit quencies may appear more clearly by reference to Fig. 5.k In this ligure the arrangement of the that internal capacitances indicated will, of V course, exist between and among the Various electrodes and between each electrode andthe surrounding shield. Inthe case -of ultra-high frequency' oscillators the controlling `capacitance which limits the value of the oscillationfrequency isthe capacitance existing between the anode and ground. If, for example, the shield 32 were connected to ground the resultant anode-ground capacitance would, in the ordinary case, consist not only of the anode-cathode capacitance Cpe but also of the anode-grid Cpg plus grid-cathode Cgk capacitance and the anode-shield capacitance Cps. If the shield 32 were floating instead of grounded no great reduction in anode-ground capacitance would result, since there would still exist capacitance between the shield and ground which Ywould result in additional anode-shield and shield-ground capacitance. hand, the-'grid is grounded for high frequency currents, as Vhas been done in the present "case, and the shield is connected to thev cathode, the onlyanode-'ground capacitance existing is the anode-gridV capacitance 'Cp'gl' VSuch arrange Y the operation of the oscillator at extremely high fre- Y If, on the other ment does increase the resultant anode-cathode Cpk capacitance but this increase is more than compensated for by the reduction in anodeground capacitance. The actual tests upon the type of oscillator which have been described and illustrated have shown thatwhereas the highest frequency obtainable with the cathode grounded and the shield, either grounded or floating, is in the neighborhood of 560 inegacycles;` by changing the connections and using the arrangement of the present invention frequencies above '780 megacycles can be obtained. The actual resultant It will be clear to those skilled in this art that while the oscillator in accordance with the present invention has been described in some detail, it is contemplated that changes may be made which, as far as the principles or the invention are concerned, will not alter the basic operation of the system.` For example, the characteristics or" the coaxial lines i2 and I4 may be varied by the shifting of the connectors i6 and 2l, as indicated in dotted lines in Fig. i. The manner in which these members may be moved is unime portant and within the skill of those working in this art. .As previously pointed out7 while the construction has been described in connection with a specic type of vacuum tube, the invention is applicable to other types of tubes suitable for high frequency work, in which the electrodes are surrounded by an external shield. A tube which provides double leads from each electrode is extremely advantageous for use at ultra-high frequencies in order that the leads may be kept as short as possible, but this is a relinement which is not necessary for the operation of my improved oscillator. Moreover, while it has been found advantageous to form the condenser b tween the grid and ground by using a part of the socket-supporting disk, as far as the principle of connecting the shield to a swinging cathode for the purpose of reducing the anode-ground capacitance is concerned, this is of no importance. It

will thus be seen that I have provided ka novel oscillator construction as well as a novel circuit for such oscillator, but that I do not intend to lirn't the invention to the particular embodiment shown, except as may be required b-y the claims which follow.

What I claim is.:

l. In a high frequency electron discharge tube oscillator of the type in which the tube includes a cathode, a grid, anode, and a generally hollow tubular shield surrounding these electrodes, and wherein the inter-electrode and electrodeshield capacitances are or appreciable value at the frequencies .to be generated, the combination of means for connecting said cathode directly to said shield, a reactive cathode conductor connecting said shield and cathode to ground, a first condenser, a resistor, means for connecting said condenser and resistor in parallel between said grid and ground, a second condenser, a reactive anode conductor, and means for serially connect- 6 ing said. second condenser andv reactive anode conductor between said anode and ground. 2. In a high frequency electron discharge tube oscillator of the type in which the tube includes a cathode, a grid, an anode, and a shield surrounding these electrodes, and wherein the interelectrode and electrode-shield capacitances are of appreciable value at the frequencies to be generated, the combination of a rst hollow resonator in the form of a coaxial line having a grounded outer conductor, means for connecting saidcathode directly to said shield, means for connecting said shield to the inner conductor of said line, a second hollow resonator in the form of a coaxial line whose outer conductor is electrically interconnected with the outer conductor of said first, coaxial line, arst condenser, a resistor, means for connecting said condenser and resistor in parallel between said grid and the grounded common outer conductor, a second condenser, and means for serially interconnecting said'second condenser between said anode and the inner conductor of said second coaxialline. 3. In an electron discharge tube circuit, a

hollow metal cylinder, a metal disk mounted.

in'and electrically coupled to said metal cylinder intermediate the ends thereof, an electron discharge device having a cathode, a grid, an

anode and an external cylindrical metal shield about these electrodes, insulating means for supporting said tube onsaid disk so that said shield is concentric with said metal cylinder, a second hollow metal cylinder mounted concentrically within the iirst metal cylinder on one side of said disk, one end of said second cylinder surrounding and electrically coupled to said metal shield, a third metal cylinder supported at one of its ends at the other end of the first metaly cylinder and extending concentrically inwardly toward the other side of said disk, and means for electrically connecting the ends of the iirst cylinder with the corresponding adjacent ends of the second and third cylinders, whereby said iirst and second cylinders form one hollow resonant cavity in the form of a coaxial line and said rst and third cylinders form a second hollow resonant cavity-in the form of a coaxial line, means for connecting the cathode to said shield and second cylinder, means'for connecting the grid'to the rst outer cylinder, and means for connecting the anode to the third cylinder.

4f. The combination according to claim 3, in which the means for connecting the grid to the outer cylinder includes a condenser formed by a side of said disk as one condenser plate, a thin layer of insulation applied to said disk, and a metal sheet 0n the other side of said insulation and forming the other condenser plate.

V5. The combinationkaccording to claim 3, in which the means for connecting the anode to the third inner cylinder includes a condenser corn-V anode to said metallic member.

6. The combination according to claim 3, in which the `me`ans for connecting the grid to the outer cylinder Aincludes a` condenser formed by a side of' said disk as one condenser plate,

a thin layer ofY insulation applied to said disk',V

and ametal sheet on -theother side of said insulation' and forming the other condenser plate; and in which means for connecting the anode to the third inner cylinderincludes a condenser comprisingV a metallic member mounted at least partially within Ysaid third' cylinder and vhaving a peripheral surface spaced slightly from a portion of the third cylinder, a dielectric intermediate said surface and the adjacent portion of the third cylinder and'means for connecting the anode to said metallic member.

7. In an electron discharge device circuit, center, mounted in and electrically coupled to said metal cylinder intermediate the ends thereof, an electron dischargedevice socket supported in the open center of said disk mounted substantiallyk coaxially relatively to said cylinder, an electron discharge device having a cathode, a grid, an anode and an external cylindrical metal shield about these electrodes, mounted in Vhollow metal cylinder, a metal disk open at its mounted concentrically within thgfirst' cylinder on the other side of said disk, with one end substantially co-planarv with the other end of the iirst cylinder and its other end spaced from saidV socket, means for electrically interconnecting the adjacent ends of the first and ythird cylinder, whereby said first and third cylinders form another hollow resonator in the formof a coaxial line, arrod concentrically positioned inside of said third cylinder, said rod having an enlarged head at one end' gradually tapering from a dialneter substantial-ly equal to that of the third cylinder down to a small diameter, a 'solid dielecsaidsocket so that the said shield is concentric with said metal cylinder, a second hollow metal cylinder mounted concentrically within rst metal cylinder on one side of said disk, one `end of said second cylinder fitting around and in elec- Y trical contact with said metal shield, a third metal cylinder supportedat one of its ends at the v other end ofV the rst metal cylinder and extending concentrically inwardly toward the other side of said disk, meansfor electrically` connecting the ends of the rst cylinder with the corresponding adjacent ends of the second and third cylinder.

8. A high frequency oscillator comprising, in combination, a hollow metal cylinder, a rmetal diskfopen atrits center, mounted in and supf ported by said metal cylinder intermediate the ends thereof, an electron discharge tube socket formed of insulating material, supported in the center of thevdisk and mounted substantially coaxially relatively to said cylinder, an electron discharge tube in said socket having a cathode, a

Y heater, a grid, an anode, and an external cylindrical metal shield about these electrodes, a plug 'extending from Vthe base of the tube and electricaliyA connected to said shield, an electrode lead extending from the base of the tube about said plug,.said tube having two leads for each electrode, the anode and grid leads being spaced diametrically opposite to one another, electrical thence through said second condenser to the iirsty tric intermediate the enlarged end oi said rod and the inner end of said third cylinder, whereby the enlarged end of said rod and the inner endof said third cylinder form a condensen'a sheet of insulating material attached to the Said other side of said disk outside of the socket, a metal sheet applied to said insulating sheet, whereby said metal sheetY and disk form a second condenser, means for connecting both of the cathode'connectors and one of the heater connectors to said rmetall plug and thence to said shield and second cylinder, means for. connecting both grid connectors to said metal sheet and cylinder, a resistor in shunt to said'second condenser, means for connecting both anode connectors to the enlarged head of said rod andV first resonator, connected to the other heater.

9. A high frequency oscillator comprising, in

ported by said metal cylinder intermediate the ends thereof, an electron discharge tube socket formed of insulating material, supported in the center of the disk and mounted substantially coaxially relatively to said cylinder, Van electron discharge tube in said socket having a cathode, a heater, a grid, an anode and an external cylindrical metal shield about these electrodes, a plug extending from the base of the tube and electrically connected to said shield, and electrode leads extending from the rbase of the tubeabout said plug, said tube having two leads for each electrode, the anode and grid leads beingspaced diametrically opposite to one another, electrical connectors in said'socket for each lead and for said plug, said socket being so positioned in 'said disk that the tube is on one side of said disk and said connections on the other side, a second hollow metal cylinder whose inner diameter Vis substantially equal to the outer diameter of said shield, mounted concentrically within the rst connectors in said socket for each lead and for Vsaid plug, said socket being so positioned in said disk that the tube is on one side of said disk and said connectors on the other side, a second hollow metal cylinder whose inner diameter is shield, mounted concentrically within the first metal cylinder on thegone side of the disk, one

' end of said cylinder being rsubstantially co-planar with one endof said first cylinder and the other I end of said second cylinder surrounding and gripping saidY metal shield, means for electrically interconnecting the adjacent ends of said rst and second' cylinders, whereby said first and second metal cylinder on one side of the disk, one end planar with one end of said first cylinder and the other end of said second cylinder surroundsubstantially equal to the outer diameter of said ing and Ygripping said metallic shield,l a ring- 'shaped metal slidable contactor engageably mounted between the first and second cylinders,

whereby said first and second cylinders form an i from said socket, a second ring-shaped slidable metal contactor engageably mounted between the first and third cylinders, 'whereby said first and vthird cylinders form another adjustable hollow resonator in the form of an adjustable coaxial line, a rod concentrically positioned inside of said third cylinder, said rod having an enlargedy head at, one end gradually tapering from a diameter substantially equal to that of a third cyl- Inder down to a smaller diameter, a solidkdielectric intermediate the enlarged end of said rod and the inner end of said third cylinder, whereby the enlarged end of said rod and the inner lend of said third cylinder form a condenser, a

sheet of insulating material attached to the other side of said disk outside of said socket, a metal sheet applied to said insulating sheet whereby said metal sheetfand said disk form a second condenser, means for connecting both the cathode connectors and one of the heater connectors to said metal plug, and thence to said shield and second cylinder, means for connecting both. grid connectors to said metal sheet and thence through said second condenser to said 'rst cylinder, a resistor in shunt` to said second condenser, means for connecting both anode connectorsy to the enlarged end of said rod, and thence through the rst, capacitor to said third cylinder, and a lead passing outwardly of said first resonator, connected to the other heater connector.

10. A combination according to claim 9 in which said second condenser and said cylinder are provided with small openings therethrough, and said lead passes through said openings and substantially parallel to said second cylinder. 11. A combination according to claim 9 in which said second condenser and said cylinder are provided with small openings therethrough,

10 and said lead passes through said openings and substantially parallel to said second cylinder in combination with a third condenser connected between said lead and said second cylinder, and a fourth condenser connected between the outer ends of said rod and said third cylinder.

12., A combination according to claim 9 in which said second condenser and said cylinder are provided with small openings therethrough, and said lead passes -through said openings and substantially parallel to said second cylinder in combination with a third condenser connected between said lead and said second cylinder, and

second condenser connected between the outer ends of said rod and said third cylinder, and a ground connected to said outer cylinder, a high potential source connected to the anodethrough said rod, and a low potential source connected to said heater lead.

WILLIAM HOTINE.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,107,387 Potter Feb. 8, 1938 2,125,969 Turner Aug. 9, 1938 2,190,712 Hansen Feb. 20, 1940 2,272,211 Kohler Feb. 10, 1942 OTHER REFERENCES Application note 108, Nov. 13, 1940, RCA Mfg. Co., 250-3622.3. 

